For protecting the safety and benefit of children, starting from July 1993, the U.S. Consumer Product Safety Commission declared that it should stop selling the traditional cigarette lighter. In view of protecting the safety of children, it is absolutely necessary and reasonable to do so. Therefore, the U.S. Consumer Product Safety Commission imposed an important regulation that requires certain cigarette lighters must be Child resistant.
However, most conventional safety lighters, presently in use, have some weaknesses on usage under a certain circumstances. For example, U.S. Pat. No. 5,096,414 owned by Zellweger, as shown in FIG. 1, discloses a striker wheel acting on a spark stone. The striker wheel is disposed between two plates which have greater diameter and are freely rotatable with respect to the wheel. Actuation of this latter is obtained by friction thanks to the deformation of the pulp of the thumb of the user, and may not be driven by a child as the pulp of the finger of children is not sufficiently thick. The problem to the above prior art is that the fact of the matter is that the pulp of the finger of a young child can still easily make contact with the striker wheel as long as the position of the child's finger is correct.
Another example is U.S. Pat. No. 5,547,370, owned by Hwang, which is a further improvement of Zellweger's patent. Similar to Zellweger's patent, Hwang's patent also includes a wheel axle mounted between two upright supports at the top of a butane wheel, two driving wheels mounted around the wheel axle between the upright supports, and a striker wheel fixedly mounted around the wheel axle and disposed in contact with a spring-supported flint below and turned by the driving wheels through the wheel axle to strike the spring-supported flint in producing sparks. The improvement is that the wheel axle is made of polygonal cross section, having two round rods at two opposite ends loosely inserted into a respective axle hole on each upright support so as to ensure a better connection between the striker wheel and the wheel axle.
However, the Hwang's patent still bears the drawbacks including higher cost and malfunctioning. Its assembly cost is higher because special care and measurement must be applied to ensure the striker wheel is located in a center position of the wheel axle. The central polygonal hole of the striker wheel must be exactly equal to the size of the polygonal wheel axle. If it is too small, it is impossible to insert the wheel axle therethrough. It is too big, the striker wheel may not be firmly held in center position. How to punch in the polygonal wheel axle through the polygonal hole of the striker wheel and how to ensure the striker wheel located in the central position of the wheel axle become a headache of Hwang's patent. Moreover, a slight clearance would be existed between the striker wheel and the wheel axle so as to facilitate the polygonal wheel axle to insert through the central polygonal hole of the striker wheel. Normally, the rotation of the wheel axle can drive the striker wheel to rotate with no problem. But, the striker wheel may gradually move aside after using for a period of time. If such condition happens, the center of the striker wheel will not remain aligning with the flint properly, that may unavoidably affect the ignition of the lighter and cause malfunction. The tip of the flint may get stuck between the driving wheel and the striker wheel.